Safety switch box



Nov. 23, 1937. w. F. SUTHERLIN SAFETY SWITCH BOX Filed Dec. 26, 1935 2 Sheets-Sheet l w n'er F. 51) er\ in ATTORN EYS Nov. 23, 1937. w. F. SUTHERLIN SAFETY SWITCH BOX 2 SheetsSheet 2 Filed Dec 26, 1955 E V W Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE SAFETY SWITCH BOX Application December 26, 1935, Serial No. 56,194

4 Claims.

This invention relates to switch boxes, and has for an object the provision of a switch box which will prevent the stealing of electric current or the jumping of meters so as to obtain electric current without the current passing through the meter.

Another object of the invention is to provide a short circuiting device in the switch box, which, when the main switch is open, automatically short circuits the work circuits.

Another object of the invention is to provide a door giving access to the main fuse in the switch box, and an automatic locking means therefor, barring access to the fuse without opening the switch.

Another object of the invention is to provide a safety switch box with means for locking the switch in open position, as when premises are unoccupied, to prevent the unauthorized closing of the switch.

Another object of the invention is the provision of a toggle make and break main switch so arranged that the work circuits are short circuited when the main switch is open.

A still further object of the invention is to provide a means for detachably mounting a meter on the switch box which may only be removed when the switch box is unlocked and opened, thereby preventing wiring around the meter.

As is well known, numerous devices are employed for stealing current from an electric lighting company by unscrupulous persons. Where the meter is separate from the switch box, devices are employed for wiring around the meter so that a part, if not all, of the current used passes around the meter instead of going through it. Also, where a building has been unoccupied,

some people have defrauded the lighting com-- pany by closing the main switch in the switch box and connect up the electric current without notifying the lighting company. It has also been known to run wires from adjoining sources around the meter to connect with the work circuits so that no current can pass through the meter. It has also been known to ground the work circuit in some concealed place and to connect the ground wire to the meter in such a way that it would not be observed and so that no current passes into the potential coil of the meter, thereby preventing the meter from operating.

All of these means of obtaining electric current dishonestly are obviated by means of my invention. In order to prevent wiring around the meter, I provide a means for detachably mounting the meter on the switch box so that no connections between the switch box and the meter are accessible. The meter may be eadily re V when desired, by authorized persons, by unlocking the switch box, whereby access to the fastening means may be obtained. I also provide a means whereby the switch may be locked in open position when the premises are vacated, thereby preventing unauthorized closing of the main switch. In order to prevent wiring around the meter from an outside source and thereby obtaining electric current, I provide a short circuiting device within the switch box, operable when the main switch is open, which short circuits the work circuits so that no current can pass into the Work circuits until the main switch is closed.

Apparatus embodying features of my invention is illustrated in the accompanying drawings forming a part of this application, in which Fig. 1 is a plan view of my improved switch box with the meter in place thereon;

Fig. 2 is a sectional view taken along the line IIII of Fig. 1;

Fig. 3 is a back View of the switch box;

Fig. 4 is a front view of the switch box and meter with the switch box cover removed and showing the electric connections; and

Fig. 5 is a diagrammatic view showing the means whereby the work circuits are short circuited and grounded when the main switch is open.

Referring to the drawings, my improved switch box comprises ends I0 and II, a bottom I2, and sides I3 and I4. A cover I6 is hinged to the side I3, by hinges I1, and may be held closed by means of a padlock I8, having its fastening element passing through a staple 20 extending through the cover I6 from the side of the switch box.

The bottom I2 is extended upwardly at the rear, as shown at I9, to support a meter 2|. The meter 2| is supported on the extension I9 by means of button head rivets 22 on the back of the meter, which are passed through suitable openings 23 and into slots 24. Moving the meter downwardly with the rivets 22 in the slots 24, fixes it securely on the extension I9.

Within the switch box is mounted a fuse block 26 made of insulating material, which carries the main fuse 21. As shown in Figs. 2 and 4 of the drawings, the meter 2I is connected electrically to the switch box by means of prongs 29 which extend downwardly into suitable sockets 3| provided in the fuse block 26, there being corresponding openings 35 in the end of the switch box to allow the prongs to enter the sockets. The line circuit connections are at 32 and the ground connections to the meter at 33. The fuse 21, as

shown in Fig. 2 of the drawings, is surrounded by a housing 353 which prevents access to the switch 28 and electrical connections around the fuse.

Extending across the upper end of the fuse block 26 is a bar 33. Carried by the meter, on each side thereof, is a resilient latch member 35 having on its lower end a hook 3'! which engages automatically with the bar (i l when the meter is mounted on the extension I9 as described. The hooks 3? may be disengaged from the bar 3% only' when the door it is unlocked and open. Access may then be had to the hooks 3 toxpress them rearwardly and disengage them from the bar 34 for the purpose of removing the meter.

The main switch 28, asshown in Fig. 2 of the drawings, is mounted upon the fuse block 25 and is connected to the line 38 at 39.' When the main switch is closed, as shown in Fig. 20f the drawings, the line passes through the switch to the main fuse 2i and from thence through a connection ii to the meter connection 32. The main switch 23, as shown in Fig. 2, comprises a bar 32 which serves to connect the line to the meter, as just described, when the switch is closed;

Mounted upon. the bar is a plate of insulat ing material as having a slot i l therein. The switch is opened and closed by means of a bell crank lever it extending across the box and movable in the slot M by means of a handle il extending outside the .box. The switch is biased to closed position or open position by means of a spring 18, connected to the plate. 53, and to the bottom of the box, as shown.

Carried by the plate 43 on the opposite side from the main switch bar 42 is a bar 4% of conducting material so disposed that when the main switch is thrown to open position, it serves to connect a plurality of terminals 5| and short circuit the electrical connections made thereto. When thrown to open position the spring '48 serves to draw the bar is down. tightly against the terminals 5|. 'It will thus be seen that the switch 28 can not be thrown to open the main circuit without short circuiting across the terminals 5|, nor can it be thrown to a position to raise the bar off the terminals 5| without, clos ing the main switch by reason of the spring 58. The handle A i is provided with a link 52 which, when the main switch is open, may be swung to a position to be engaged by the lock i8 when the main switch 28 is opened. 'The main switch may thus be locked in open position by means of the lock it, which serves to close the switch box. By this means, unauthorizedclosing of the switch is prevented.

As is customary in switch boxes, access to. the main fuse 2'2! is had by means of a small spring pressed door 53: On the under side of the door 53 is provided a strap 5 through which a bolt 55 passes. The bolt 5% is actuated by means of a pin 58 extending inwardly of the'box in the path of the switch lever Qt, so that when the switch 28 is thrown to closed position, as shown in Fig. 2, the lever it strikes the pin 53 and moves the bolt 56 into locking position. When the switch 28 is opened, the bolt 55 falls by gravity to disengage it from the strap 54. By this arrangement it is necessary, in order to gain access to the main fuse 27, to open the main switch 28.

Within the switch box is located a ground strip of conducting material 59, which ground strip is connected, as shown in Fig. 4, to any suitable.

ground connection, as shown at 6|. One of the terminals 5| is connected to the ground strip 59 within the box by means of a connection 62 so that when the main switch is thrown to open position with the conducting bar 49 across the terminals 5|, all circuits leading thereto are grounded. It is also preferable that one of the terminals 5! also be connected directly to the ground outside the box, as shown in the drawings.

Referring now to Fig. 5, I show diagrammatically the operation of the short circuiting feature of my invention. The line circuit is shown at 38 and passes through the switch bar A2, when the switch is in closed position, thence through the main fuse 2i and meter 2|. From the meter 2|, the circuit continues through a connection 64 and house fuse 56 to a work circuit 61, thence through a light or other current consuming device 68., From the current consuming device the current continues through a house fuse 69 to the ground strip 553,- and from thence back through the meter 2| to the return line H.

In accordance with my invention, I connect a conductor 12 to the work circuit beyond the fuse to, and from thence to one of theterminals conductor 49 serves to short circuit the work circuit so that no current can be obtained.

From the foregoing, it will be apparent that I have devised an improved switch box which is simple and economical of manufacture, and which is adapted to prevent theft of current. The mounting of the meter on the switch box with the prong and socket connections prevents tampering with the connections between the meter and the switch box, while the means for locking the meter on to the switch box prevents its unauthorized removal for the purpose of tampering with the connections. The means provided for locking the switch, in open position prevents unauthorized closing of the switch where previously unoccupied premises become occupied. The short circulating device incorporated in, the switch box insures thatif wiring from an outside source is carried in around the meter no current can be obtained, because the work circuits are automatically grounded.

While I have shown my invention in but one form, it will be obvious to those skilled in the art C .switch box connected to the meter coils, and a double throw spring pressed switch in the switch box so disposed that when closed on one side the power line is connected to the work circuit through the meter coils, and when closed'on the other side the work circuit beyond the mter'is connected to the ground.

2. In switch apparatus of the character de scribed, a switch box, a meter, ground connection terminals in the switch box, a work circuit, terminals in the switch box for the work circuit and the meter coils, a double throw spring pressed switch in the switch box for controlling the work circuit in one position, a connection from the other side of the switch to the work circuit beyond the meter, a connection from said other side of the switch to the ground, said connections being placed in circuit by the double throw switch when the work circuit through the switch box and meter is open.

3. In switch apparatus of the character described, a switch box, a meter mounted on the switch box, a door and lock therefor on the switch box, a spring pressed double throw switch mounted in the switch box, a line circuit leading to one side of the switch, a work circuit adapted to be connected to the line circuit by the switch in one position through the switch and the meter coils, a connection from the other side of the switch to the ground, a terminal at said other side of the switch connected to the work circuit beyond the meter, and a conductor carried by the switch to connect said ground connection and said terminal when the work circuit is open.

4. In apparatus of the character described, a switch box, a meter mounted thereon, a door and lock for the switch box, terminals in the switch box connected to a line circuit, the meter coils, a work circuit, and to the ground, and a double throw switch disposed when closed on one side to connect the line circuit with the meter coils and work circuit through said terminals, and when closed on the other side to disconnect the line circuit and connect the work circuit to the ground through said terminals.

WALTER F. SUTHERLIN. 

